Prelabor rupture of the membranes at term: when to induce labor?

To determine the significant predictors of clinical chorioamionitis and neonatal infection in patients with prelabor rupture of the membranes at term, and to apply this information to determination of optimal timing of labor induction.

A retrospective case control series of women at > or =37 weeks' with prelabor rupture of the membranes. The study group consisted of women with evidence of maternal or neonatal infection. Controls had no evidence of infection. Three types of management were compared. (1) Immediate induction of labor, (2) expectant management up to 24 h followed by induction of labor if still necessary, or (3) expectant management for over 24 h. Univariate and multivariate analyses were performed by stepwise logistic regression (SPSS software package). The size of the study and the control groups was calculated for a 90% power with two sided P value of 0.05 in order to demonstrate an odds ratio of 2 for expectant management (two groups: early and late) versus immediate induction of labor (132 and 279 women in the study and the control groups, respectively).

The rate of expectant management for over 24 h versus expectant management until 24 h followed by induction of labor when still necessary, was higher among cases than among controls ( OR = 1.84; P < 0.017; 95% CI, 1.127-3.003). Conversely, the rate of immediate induction of labor versus expectant management until 24 h followed by induction of labor when still necessary, was also higher among cases ( OR = 2.66; P < 0.001; 95% CI, 0.222-0.644).

In women with prelabor rupture of the membranes at term, the best approach is to induce labor if spontaneous labor has not begun after 24 h.